Not Applicable.
Not Applicable.
1. Field of Invention
This invention relates generally to the field of movable seating, and more particularly to chairs that are self-adjustable in seat back rest angle during use.
2. Description of Related Art
Prior movable chairs having adjustable backrest frames have provided frame members with internal springs or externally connected spring members to control movement of the backrest frames. A typical flexible backrest is described in U.S. Pat. No. 5,039,163, issued to Tolleson, which discloses a chair including depending leg members and a hollow support frame having at least two open ends terminating beneath the seat assembly of the chair. The chair includes a flexible backrest assembly including a pair of hollow backrest frame members having at least two open frame ends extending downward and beneath the seat assembly. Each open end of the hollow backrest frame contains at least one flexible spring member inserted therein the hollow backrest frame, the spring member composed of a resilient, generally narrow material of rectangular cross-section, with each end of each spring member enclosed by a U-shaped bracket of light weight metal. Each open frame end is aligned with an opposing open end of the tubular seat frame. The U-shaped bracket on each end of each spring member inserts respectively into the open frame end, and the open end of the seat frame. Two spring members and four U-shaped brackets are required for one set of flexible connections of the backrest frame and the seat frame. Additionally, a second set of spring members and U-shaped brackets are required to be positioned interior and alongside each first set of two spring members and four U-shaped brackets inside the backrest frame and the seat frame. The second set of spring members have additional U-shaped brackets enclosing each end of each spring member, with the U-shaped brackets enclosed by sections of hollow support tubes, which are mounted alongside each open end of the backrest frame and the seat frame. Therefore, the flexible backrest assembly requires four spring members, eight U-shaped brackets of a specific size and length, and two additional hollow support tubes mounted alongside each open end of the hollow backrest frame member and the hollow seat frame member. Each spring member is permanently affixed at the opposed ends in place within each U-shaped bracket with rivets to restrain the opposed ends within each bracket while allowing the middle section of each spring member to flex. Each U-shaped bracket includes an exposed flange end that contacts an opposed flange end of an adjacent U-shaped bracket to limit the flex of each spring member and to limit the angular movement of the upper backrest portion of the backrest frame.
U.S. Pat. No. 4,869,552, issued to Tolleson et al., discloses a chair including a seat backrest upstanding frame and a lower backrest part with hollow ends. The hollow ends include depending members aligned with the hollow upstanding frame ends, with a flexible, elongated, flat or blade spring member having opposite ends secured into the center of two opposing holder members for insertion in a concentric orientation into each respective hollow end of the depending members. The open ends of each holder member have stop flange formations that protrude outwardly thereon and are spaced apart from the respective opposite stop flange formations on an adjacent holder member. The stop flanges limit the angle of flexure of the spring member by engagement of the flanges. The depending members require at least two spring members for the lower backrest, require at least two holder members for each spring member, and require an exterior flexible cover to minimize the pinching of a user by the movement of the stop flanges together.
U.S. Pat. No. 4,603,904, issued to Tolleson et al., discloses a seat frame including an upper backrest part and a lower backrest part, each having hollow ends. Each hollow end includes an inserted strut being connected to a pair of spaced apart depending members. A flexible, elongated, cylindrical spring member such as a cable is secured into the center of two opposing depending members which hold the ends of the spring member and which are inserted in a concentric orientation into each respective hollow end of the upper backrest part and the lower backrest part. The depending members require at least two spring members such as lengths of cables for insertion into each upper and lower backrest part of the backrest, require at least two holder members for each spring member, and require an exterior flexible cover to minimize the pinching of a user by the movement of the strut and depending members during flexure of the cylindrical spring member.
The prior adjustable seat support frames are generally frames having a plurality of spring elements within tubular frames underneath the seat cushion frame, or spring members inserted concentrically within the support frames between upper backrest portions and lower backrest portions. Each spring element or spring member is flexible but is surrounded by stop members or flanges for limiting flex over a preferred angle of flexure when a user is seated and applies weight against the backrest. Multiple depending members and enclosing brackets are required to support the spring elements and to provide adequate structural support for each portion of the backrest. There is a need for an improved seat spring system that maintains sufficient tension to limit the angle of flexure for a backrest while minimizing the required parts for proper operation. There is also a need to provide an improved seat spring system that reduces the manufacturing costs for the materials utilized to make the spring elements and to support the spring elements.
Therefore, it is an object of the present invention to provide a chair having an improved seat spring system that provides a resiliently flexible spring backrest having controlled angular range of motion of the chair backrest frame.
It is another object of the present invention to provide a chair having an improved seat system that includes a minimum of parts to reduce production costs and assembly time.
It is another object of the present invention to provide a chair having an improved seat spring system that includes a minimum of spring elements, enclosing tubes, and holder brackets.
It is another object of the present invention to provide a chair having an improved seat spring system including a spring element that is contained by one holder bracket at each end of the spring element, with each holder bracket directly connected to separate members of the chair frame.
It is another object of the present invention to provide a pair of holder brackets enclosing one spring element, with each holder bracket having an inherent angled flange oriented to control the angular range of motion of the spring element.
Other subjects and advantages will be accomplished by the present invention which includes an improved seat spring system for a portable chair. The chair includes a seat assembly which includes depending leg members and a support frame including a seat support frame having a pair of seat support frame members, each having ends being directed toward the rear of the chair, and a backrest frame having a pair of spaced apart backrest frame members upstanding relative to the pair of seat support frame members. The backrest frame members include ends extending beneath the seat support frame and arranged in registry with respective ends of the seat support frame members, the ends of the backrest frame members are positioned in spaced apart alignment across a gap between each end of the backrest frame member and the respective end of each seat support frame member.
The chair includes a seat spring system for providing a flexible spring backrest for the chair. The seat spring system includes a spring element being shaped and sized for being positioned adjacent the gap between each backrest frame member and each respective seat support frame member. The spring element includes a mid-section being aligned beside the gap, with the spring element having opposed ends being extended a selected distance along either frame member at each gap.
A first holder receptor and a second holder receptor are paired and separately attachable to each opposed end of the spring element. The first and second holder receptors being elongated, having a planar top portion, a planar bottom portion, a closed end, and being substantially U-shaped in cross-section. The first holder receptor includes an opening end being faced towards and in registry alignment with the second holder having an opening end, and each holder receptor having the closed end opposite the opening end. Each holder receptor opening end is positioned apart from a selected space from the other holder receptor opening end, with the selected space being positioned adjacent and to the side of each respective gap. The spring element is positioned therebetween the opening ends of each aligned holder receptor. The spring element mid-section is oriented in side-by-side configuration beside the gap between the frame members. The first holder receptor closed end is secured to an inwards faced side of the backrest frame member, and the second holder receptor closed end is secured to an inwards faced side of the seat support frame member. Therefore, the spring element is positioned essentially off-center relative to the longitudinal center line of each aligned backrest frame member and seat support frame member. The spring element and attached holder receptors are installed adjacent to, and not within, the aligned seat support frame and the backrest frame.
With the spring element mid-section being positioned adjacent the gap in the side-by-side configuration, the spring element provides controlled angular range of motion of the backrest frame when moved by the chair occupant relative to the seat support frame. The spring element concurrently provides structural continuity between each aligned backrest frame member and seat support frame member while the spring element is constrained from excessive flex by each respective first holder receptor and second holder receptor aligned beside the aligned seat support frame and the backrest frame. The material of the spring element is capable of repetitive flexing and being returned to the non-flexed position.
The holder receptors are elongated and include a single layer wall being substantially U-shaped in cross-section. The U-shaped holder receptors provide for restrained enclosure of each respective opposed end of the spring element. Each receptor having an opening defined by a first projection end and an adjacent second end of each receptor, the opening of each receptor being designed to removably receive one each of the opposed ends of the spring element, the opening of the first receptor being faced toward the opening of the second receptor. The first receptor having a first closed end opposite the first projection end and the second end, the second receptor having a second closed end opposite the first projection end and the second end of the second receptor, each opposed end of the spring element being positioned respectively internal of the first closed end and internal of the second closed end of the first receptor and the second receptor. The first receptor is connected in side-by-side configuration along the chair interior of one of the backrest frame members, with the second receptor connected in side-by-side configuration along the respective aligned seat support frame member. With the spring element positioned within each single layer walled, U-shaped holder receptor, each spring element can be independently replaced by removing each restraining a connector and inserting a spring element of similar shape but with more, or less, rigidity for preferential control of the angular range of motion of the backrest frame.